Thiol-ene polymer metal oxide nanoparticle high refractive index composites

ABSTRACT

A bulk polymer composite comprising a thiol-ene polymer matrix, or the corresponding polymers derived from a phosphinyl, selenol, or arsinyl monomer, and metal oxide nanoparticles dispersed within said matrix, said nanoparticles being bonded to polymer molecules contained in the matrix. Terpolymers that further comprise repeat units derived from a molecular metal oxide cluster, and composites in which such terpolymers function as a matrix for metal oxide nanoparticles are also disclosed.

FIELD OF THE INVENTION

The present invention generally relates to a high refractive indexmaterial comprising a polymer having a high degree of cross-linking andcontaining polarizable elements. The present invention further relatesto a method for preparing high refractive index, transparent materials.

BACKGROUND OF THE INVENTION

Organic polymers are used for many optical applications, the largestbeing in the area of consumer eyewear. In this application, organicpolymers afford a variety of properties including low density andresistance to impacts and scratches. Organic polymers may also beprocessed into what are referred to as progressive lenses that have agraded refractive index to accommodate both near-sighted and far-sightedcorrections. The organic polymers typically used in contemporary eyewearapplications are commonly, but not exclusively, composed ofpolymethracrylates, polycarbonates, or polythiourethanes. The opticalparameters of importance in the choice of polymer for this applicationare the refractive index, Abbe number, and optical clarity. Materialscurrently in use typically are in the refractive index range (“R.I.”) of1.65-1.68, though materials with R.I. of 1.70 or above have beensynthesized. The Abbe number represents the chromatic dispersion oflight, which is the refractive index, measured at specific wavelengths(specifically the Fraunhofer d, f, and c wavelengths). The Abbe numberis inversely proportional to the chromatic dispersion. It generallyvaries between 60, which translates to a very low chromatic dispersionand 30, which is a highly chromatic material. For eyewear applications,the Abbe numbers in the range of 35-40 are acceptable and are typicalfor the organic polymers used.

For optical applications in general and eyewear in particular, thesynthesis of new polymers with refractive indices >1.65 and acceptableAbbe numbers is of considerable importance. Higher refractive indexmaterials will permit smaller, lighter weight lenses to be used andprovide a much broader graded index for progressive lenses. The materialmodification that leads to higher refractive indices is theincorporation of highly polarizable atoms and ions. Incorporating suchpolarizable groups has been the standard protocol used to develop newhigh R.I. polymers. The electronic polarizability is a tensor propertyof an atom or molecule that measures the distortion of the electroncloud in the presence of an applied electric field (which can be anoptical field). The more the electron cloud can be distorted, the higherthe refractive index. The characteristics of atomic and molecularelectronic structure that yield large polarizabilities are wellunderstood and can be predicted from basic chemical principles. Inparticular, the more electronegative an atom is the less polarizable itwill be, hence late first-row elements such as F, O and N tend to yieldlower refractive index materials. Better choices are 2^(nd), 3^(rd) or4^(th) row main group elements such as S (which is currently used inorder to increase the refractive index in many polymeric materials), P,and Sn. From a molecular standpoint, the higher electronegativity of thefirst row can be overcome by delocalization of the electrons acrossseveral atoms. Aromatics are more polarizable than saturatedhydrocarbons and compounds such as propylene carbonate anddimethylformamide have high dielectric constants.

Stiegman, U.S. Pat. No. 8,470,948, discloses a series of thiol-ene basedbulk polymers having high refractive indices and good structuralproperties.

SUMMARY OF THE INVENTION

In various embodiment, the present invention comprises a bulk polymercomposite comprising a thiol-ene polymer matrix, or a matrix comprisinga corresponding polymer derived from a phosphinyl, selenol, or arsinylmonomer, and metal oxide nanoparticles dispersed within the matrix, saidnanoparticles being bonded to polymer molecules contained in the matrix.In certain preferred embodiments, the polymer matrix comprises a matrixcorresponding to the structure:

wherein:

M is a main group element, a transition metal element, or an organicmoiety;

X is a main group element selected from the group consisting of S, P,Se, As and combinations thereof;

R₁ is, independently of any other R₁ in the polymer, a direct bondbetween M and the ethylene group depicted between M and X or ahydrocarbyl linking moiety having between 1 and about 9 carbon atoms;

R₂ is a hydrocarbyl moiety having between 1 and about 9 carbon atoms;

R₃ is an organic linking group;

Y has a value of 0, 1, 2, 3, or 4;

Z has a value of 0, 1, 2, 3, or 4;

YY has a value of 0, 1 or 2; and

Y, YY, and Z are such that the total number of moieties bonded to M is3, 4, 5, or 6;

and n represents the number of repeat units in the polymer,

and wherein at least 90% of functional groups in the bulk polymer arereacted.

The invention is further directed to a process for the preparation of abulk polymer composite comprising a thiol-ene polymer matrix or a matrixcomprising a corresponding polymer derived from a phosphinyl, selenol,or arsinyl monomer, and nanoparticles dispersed within said matrix. Inthe novel method, a mixture is formed comprising a first multifunctionalmonomer comprising vinyl groups, a second multifunctional polymercomprising thiol moieties or moieties comprising phosphinyl, selenol, orarsinyl groups, and nanoparticles comprising a metal oxide or a metaloxide that has been functionalized with a ligand that is reactive with afunctional group of the first multifunctional monomer or the secondmultifunctional monomer. The first multifunctional monomer is reactedwith the second multifunctional monomer to form a polymer matrix withinwhich the nanoparticles are dispersed, the metal oxide or ligand on thenanoparticles reacting with functional groups of the firstmultifunctional monomer, functional groups of the second multifunctionalmonomer, or functional groups of a polymer produced by reaction of thefirst monomer and the second monomer.

The invention is further directed to a terpolymer or higher polymercomprising repeat units derived from a first multifunctional monomerhaving 2 to 4 vinyl groups, a polythiol, preferably a dithiol, or acorresponding phosphinyl, selenol or arsinyl monomer, and a molecularmetal oxide cluster.

The invention is further directed to A process for preparing terpolymeror higher polymer comprising reacting a first multifunctional monomerhaving 2 to 4 vinyl groups, a polythiol, preferably a dithiol, or othercorresponding phosphinyl, selenol or arsinyl monomer, and a molecularmetal oxide cluster.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts chemical reaction of acrylic acid on the surface ofparticles.

FIG. 2 depicts fabrication of polymer-nanoparticle composites.

DETAILED DESCRIPTION OF THE EMBODIMENT(S) OF THE INVENTION

The present invention is generally directed to a high molecular weightbulk polymer composite having high refractive index. In one aspect, thepresent invention is directed to a high refractive index materialcomprising a polymer and metal oxide nanoparticles and having a highdegree of cross-linking and containing polarizable elements. Anotheraspect of this invention is directed to a high refractive index materialcomprising a polymer and functionalized molecular metal oxide clustercompounds having a high degree of cross-linking and containingpolarizable elements.

Transition metal oxide nanoparticles are incorporated into the thiol-enepolymers according to this invention to enhance structural and opticalproperties. These oxide nanoparticles may comprise, for example,titania, hafnia, zirconia, molybdenum oxide tungsten oxide and niobiumoxide. The nanoparticles are preferably ≦100 nm in size, typically ˜30nm. They are preferably functionalized by derivatization reaction with amonomer that comprises a vinyl group and a functional group reactivewith said metal oxide and a vinyl group, to generate ligands comprisingvinyl groups on the surface. Preferred derivatizing agents includeacrylic and methacrylic acid, the carboxylic acid group of which isreactive with metal hydroxides or metal oxides on the particle surface.The vinyl groups of the ligands cross-link into the thiol-ene polymer toform a uniform, hard, transparent material. As bonded via an acrylic,methacrylic or other ligand that comprises a vinyl group, thenanoparticles are dispersed in a thiol-ene polymer matrix and covalentlybonded to polymer molecules contained in the matrix.

In other embodiments, molecular metal-oxide cluster compounds areincorporated into the thiol-ene polymers according to this invention toenhance optical properties. Advantageously, the molecular clustercompounds may also contain acrylic or methacrylic ligands. These ligandscan cross-link into the thiol-ene polymer to form a uniform, hard,transparent material.

The composite material preferably contains at least about 0.5 wt % ofthe metal oxide, for example between about 0.5 wt % and about 10 wt %.It is preferred that the composite material contain more than 1 wt %,such as between about 1 wt % and about 10 wt % of the metal oxidenanoparticles and/or metal oxide cluster compounds. Still otherembodiments contain at least 3 wt % or at least 5 wt % metal oxidenanoparticles and/or metal oxide cluster compounds. These proportionsare on an oxide equivalent basis, as in some instances, of course, theoxide may be, for example, in the methacrylate form or other form.

The incorporation of the metal oxide nanoparticles and/or metal oxidecluster compounds has been shown to increase refractive index in thesepolymers. For example, incorporation of ZrO₂ into a TVS-EDT polymeraccording to this invention yields a refractive index of 1.668 incomparison to 1.656 for the TVS-EDT polymer itself. The compositematerial is therefore at the high end of the refractive index range foroptical polymers.

The metal oxide nanoparticles and cluster compounds have a highcross-linking density to the polymer, such that there is a very highnumber of bonds to the polymer, which further enhances the mechanicalproperties of the polymer composite in comparison to the polymer alone.

The polymer nanoparticle composite materials exhibit a very low surfaceenergy due to the “lotus leaf effect” brought about by the nanoparticlestructures at the surface, and are especially hydrophobic. This isdesirable for many optical applications where repulsion of water anddebris are important.

The resulting polymer-nanoparticle composites therefore exhibit highrefractive index, high strength, high Young's modulus, high rigidity,and high hydrophobicity; all of which are important properties foroptical materials.

The present invention further relates to a method for preparing highrefractive index transparent materials.

The incorporation of the metal oxide nanoparticles has been shown toincrease refractive index in these polymers. For example, incorporationof ZrO₂ into a TVS-EDT polymer according to this invention yields arefractive index of 1.668 in comparison to 1.656 for the TVS-EDT polymeritself. The composite material is therefore at the high end of therefractive index range for optical polymers.

The incorporation of the molecular cluster compounds has been shown toincrease refractive index in these polymers. For example, incorporationof Zr₄O₂(Methacrylate)₁₂ into a TVS-BDDT polymer according to thisinvention yields a refractive index of 1.715 in comparison to 1.687 forthe TVS-EDT polymer itself. The composite material is therefore at thehigh end of the refractive index range for optical polymers.

The structure of the following detailed description is that first thetext from the inventor's issued U.S. Pat. No. 8,470,948 is incorporatedto describe exemplary high refractive index polymers into which,according to the present invention, transition metal oxide compounds areincorporated. Then, under the headings FABRICATION OFPOLYMER/NANOPARTICLE COMPOSITES and FABRICATION OF POLYMER/OXO-ZIRCONIUMCLUSTER COMPOSITES there are descriptions of two embodiments of thecurrent invention. One such embodiment is for nanoparticles, whichincrease refractive index, mechanical properties and surface energy. Adisadvantage to nanoparticles is that they are relatively insoluble inmonomer solutions so high loadings cannot be achieved. The secondembodiment makes use of metal oxide molecular cluster compounds thatcomprise functional groups that are reactive with either the vinylfunctionality of another multifunctional monomer or the thiolfunctionality of the dithiol or polythiol monomer. Other comparablepolyphosphinyl, polyselenol, or polyarsinyl monomers may also be used.The cluster compounds have the advantage of better and more controlledsolubility. The clusters tend to improve refractive index but do nothave much effect on the structural or surface properties.

In some embodiments, the present invention is directed to a method forpreparing a high refractive index material comprising anorganic/inorganic hybrid polymer having a high degree of cross-linkingand comprising organic and inorganic moieties. In general, anorganic/inorganic hybrid polymer comprises repeat units comprising atomstypically found in organic and biochemical molecules, in particular,carbon, hydrogen, sulfur, nitrogen, and oxygen in addition to atoms thatare transition metal elements or main group elements, for example, Si,Ge, As, Se, Te, and Sb. In some preferred embodiments, theorganic/inorganic hybrid polymer having a high degree of cross-linkingand comprising organic and inorganic moieties is prepared by thiol-eneaddition reactions. Accordingly, in some preferred embodiments, therepeat units of the polymer comprise thiol-ene addition products.

In some embodiments, the present invention is directed to a method forpreparing a high refractive index material comprising an organic polymerhaving a high degree of cross-linking. Transition metal elements andmain group elements other than carbon, hydrogen, sulfur, nitrogen, andoxygen are generally not present in the organic polymers of the presentinvention, although their presence is not excluded. By “organic” it ismeant that the polymer generally comprises carbon-based repeat units andhas characteristics typical of organic polymers. As is known, organicpolymers generally comprise H, C, S, N, and O, but may also comprisetransition metals and main group elements other than H, C, S, N, and O.Transition metal elements and main group elements other than carbon,hydrogen, sulfur, nitrogen, and oxygen are thus generally not present inthe organic polymers of the present invention, although their presenceis not excluded. In some preferred embodiments, the organic polymerhaving a high degree of cross-linking is prepared by thiol-ene additionreactions. Accordingly, in some preferred embodiments, the repeat unitsof the polymer comprise thiol-ene addition products.

In some preferred embodiments, the repeat units of the polymers of thepresent invention are established by a thiol-ene addition reaction.Thiol-ene reactions involve the addition of an R—S—H bond across adouble or triple bond by either a free radical or ionic mechanism.Thiol-ene reactions covalently bond the monomers into repeat units andare used in the present invention for preparing a high molecular weightpolymer having properties useful for preparing lens materials andflexible light guides. In some embodiments, the repeat units of thepolymers of the present invention are formed by the reaction ofpolarizable groups terminated with thiol or vinyl or thiol and vinylgroups to covalently bond through thiol-vinyl addition chemistry intothe repeat units of a high polymer. The high molecular weight polymersof the present invention that are derived from the thiol-ene additionreaction are characterized by high refractive indices and high Abbenumbers.

In some embodiments, the highly cross-linked polymer of the presentinvention is a high refractive index material. Both highly cross-linked,organic/inorganic hybrid polymers and highly cross-linked, organicpolymers have been prepared to have high refractive indices. Suchmaterials, when manufactured to have a high degree of hardness, areparticularly useful in optical applications, such as lenses. The highlycross-linked polymer of the present invention may be manufactured to arefractive index of at least 1.55, and in some embodiments, therefractive index of the material comprising the cross-linked polymer ofthe present invention is at least 1.60, such as at least 1.65, at least1.70, at least 1.75, or even at least 1.80. In some embodiments, a highrefractive index of the materials of the present invention is achievedby limiting the proportion of or even excluding electronegative atomshaving electronegativities above about 2.65 (Pauling scale), such asoxygen, nitrogen, fluoride, chloride and the like in the cross-linkedpolymer of the present invention. While some electronegative atoms maybe present in a cross-linked polymer and the goal of high refractiveindex may still be achieved, preferably, electronegative atoms areexcluded from the cross-linked polymer of the present invention. In someembodiments, moieties comprising electronegative atoms, such as oxygenand nitrogen, are included in the repeat units of the polymer, andalthough the refractive index may slightly lower compared to polymerswithout such atoms, it has been found that the inclusion of thesemoieties results in polymers having excellent mechanical properties,such as flexibility.

In some embodiments, the highly cross-linked polymer of the presentinvention has an Abbe number of at least 30, such as at least 32, atleast 34, at least 36, or even at least 38. Both cross-linked,organic/inorganic hybrid polymers and cross-linked, organic polymershave been prepared having high Abbe numbers. A particular advantage ofthe cross-linked polymer of the present invention of the presentinvention is the achievement of a material that combines a highrefractive index with a higher Abbe number than is normally associatedwith high refractive index materials. The cross-linked polymer of thepresent invention therefore may be particular useful for fabricatingcorrective lenses, i.e., eyeglasses.

In one preferred embodiment, the material of the present invention has arefractive index of at least 1.65 combined with an Abbe number of atleast 38.

In some embodiments, the highly cross-linked polymer of the presentinvention has a high degree of microhardness, which also contributes toits usefulness as a lens material, e.g., for corrective lenses. In someembodiments, the cross-linked polymer of the present invention has beenmanufactured into a flexible material which is important for ophthalmicimplants such as interocular lens in which a foldable optic that opensupon insertion minimizes the size of the surgical incision required.

In some embodiments, the highly cross-linked polymer of the presentinvention has a high degree of flexibility, which is useful forapplications where a flexible, high refractive index material isdesirable, such as flexible light guides, optoelectron fabrication,optical adhesives, encapsulants for organic Light Emitting Diode (LED)devices, microlens components for charge couple devices (CCD).

The cross-linked polymer of the present invention has the followinggeneral structure:

Alternatively:

In some embodiments of structure (I), M is a main group element capableof achieving a coordination number of 3, 4, 5, or 6. In some embodimentsof structure (I), M is a transition metal element capable of achieving acoordination number of 3, 4, 5, or 6. Stated another way, in embodimentswherein M is a main group element or a transition metal element, the Mmoiety can achieve a trivalent coordination sphere, tetravalentcoordination sphere, pentavalent coordination sphere, or a hexavalentcoordination sphere. In some embodiments of Structure (I), M is anorganic moiety bonded to three or more substituents as are depicted inStructure (I), preferably at least four substituents.

In some preferred embodiments, M is the transition metal element and iscapable of achieving a coordination number of 3 (trivalent coordinationsphere). In some preferred embodiments, M is the transition metalelement and is capable of achieving a coordination number of 4(tetravalent coordination sphere). In embodiments wherein M is atransition metal element, the polymer of the present invention is ahighly cross-linked, organic/inorganic hybrid polymer. In some preferredembodiments, the transition metal may be selected from among Mn, Zr, Ti,and Cr.

In some embodiments, M is a main group element capable of achieving acoordination number of 3 (trivalent coordination sphere). In someembodiments, M is a main group element capable of achieving acoordination number of 4 (tetravalent coordination sphere). Inembodiments wherein M is a main group element, the polymer of thepresent invention is a highly cross-linked, organic/inorganic hybridpolymer. Preferably, the main group element capable of forming atrivalent or tetravalent coordination sphere is a second, third, orfourth row main group element having an electronegativity less than 2.65(Pauling scale). In some preferred embodiments, the main group elementsmay be selected from among Si, Ge, or Sn.

In some embodiments of structure (I), M is an organic moiety bonded tothe substituents shown in Structure (I). In some embodiments wherein Mis an organic moiety, the polymer of the present invention is thecross-linked, organic polymer. In some preferred embodiments ofstructure (I), M is derived from an organic moiety comprising at leasttwo substituents comprising ethylene moieties, e.g., carbon-carbondouble bonds having the structure —C═C—, such as vinyl or allyl groups,preferably at least three substituents comprising ethylene moieties.

In structure (I), the coordination number, i.e., the number ofsubstituents bonded thereto, of M is dictated by the values of Y, YY,and Z. Y may have a value of 0, 1, 2, 3 or 4. Preferably, Y has a valueof 4 such that there are no R₂ groups. In structure (I), Z may have avalue of 0, 1, 2, 3 or 4. Preferably, Z has a value of 1 or 2. Instructure (I), YY may have a value of 0, 1, or 2. Preferably, YY has avalue of 0. The values of Y, YY, and Z may be such that the M moiety hasbonded thereto 3, 4, 5, or 6 substituent moieties. Preferably, thevalues of Y, YY, and Z are such that the total number of moieties bondedto M is 3 (e.g., M is a transition metal element or main group elementthat forms a trivalent coordination sphere or M is an organic moietyhaving three substituents) or 4 (e.g., M is a transition metal elementor main group element that forms a tetravalent coordination sphere or Mis an organic moiety having four substituents).

As stated above, preferably, Z has a value of 1 or 2 and YY has a valueof 0, such that there are 3 or 4 moieties having the structure

R₁—CH₂—CH₂—X

bonded to M.

In structure (I), X is a main group element selected from among S, P,As, Se, Te, Sb, and combinations thereof. In some preferred embodimentswherein X is a main group element, X is selected from among S, Se, orTe. In some preferred embodiments wherein X is a main group element, Xis sulfur.

In structure (I), the R₁ moiety is, independently of any other R₁ in thepolymer, a direct bond between M and the ethylene group depicted betweenM and X or a hydrocarbyl linking moiety having between 1 and about 9carbon atoms, such as methylene, ethylene, n-propylene, iso-propylene,n-butylene, iso-butylene, tert-butylene, n-pentylene, isopentylene,neopentylene, hexylenes, heptylenes, octylenes, and nonylenes. Inpreferred embodiments, each R₁ moiety is identical. In some preferredembodiments, R₁ is a direct bond between M and the ethylene groupdepicted between R₁ and X. In some preferred embodiments, R₁ is ahydrocarbyl linking moiety having between 1 and 4 carbon atoms, such asmethylene, ethylene, n-propylene, iso-propylene, n-butylene,iso-butylene, and tert-butylene. In some preferred embodiments, R₁ ismethylene.

In structure (I), R₂ is a hydrocarbyl moiety, e.g., alkyls, alkenyls,alkynyls, aryls, and aralkyls, having between 1 and about 9 carbonatoms. As stated above, in structure (I), Y may have a value of 0, 1, 2,3 or 4. In preferred embodiments, Y is 4, and the R₂ moiety is notpresent in the polymer generally depicted by Structure (I).

In structure (I), R₃ is an organic linking group that links together Xmain group elements, the organic linking group may be either ahydrocarbyl, e.g., alkyl, alkenyl, alkynyl, aryl, or aralkyl, or may beany of alkyl, alkenyl, alkynyl, aryl, or aralkyl further comprisingheteroatoms.

In some embodiments, R₃ is an organic linking group that is ahydrocarbyl, such as an alkyl, substituted alkyl, cycloalkyl,substituted cycloalkyl, alkenyl, substituted alkenyl, alkynyl,substituted alkynyl, aryl, or substituted aryl. Alkyl R₃ linking groupsgenerally have between 1 and about 10 carbon atoms, preferably between 1and 5 carbon atoms. Exemplary alkyl linking groups include methylene,ethylene, n-propylene, iso-propylene, n-butylene, iso-butylene,tert-butylene, n-pentylene, isopentylene, neopentylene, hexylenes,heptylenes, octylenes, nonylenes, and decylenes. Preferred alkyl linkinggroups include methylene, ethylene, n-propylene, iso-propylene,n-butylene, iso-butylene, tert-butylene, n-pentylene, isopentylene, andneopentylene. With regard to cycloalkyl, alkenyl, alkynyl, and aryllinking groups, the number of carbon atoms may be greater, such asbetween 2 and about 24 carbon atoms, preferably between 2 and about 20carbon atoms, more preferably between 2 and about 14 carbon atoms.Exemplary cycloalkyl linking groups include cyclopentyl, cyclohexyl,cycloheptyl, cyclooctyl, and the like. Exemplary aryl groups includephenyls, biphenyls, naphthyls, anthracenyls, phenanthrenyls, and thelike. The use of alkenyl, alkynyl, and aryl linking groups isparticularly advantageous since these linking groups incorporateunsaturated bonds into to the cross-linked polymer, which has been foundto increase the refractive index of the resultant material. This effectis particularly achieved when the linking group incorporates conjugateddouble and triple bonds into the resultant material. Linking groupscomprising conjugated doubled and triple bonds include alkenyl, alkynyl,or aryl in which the number of conjugated double bonds is at least two,such as between 2 and 16, preferably between 2 and about 10, orpreferably between 2 and about 5. A high number of conjugated doublebonds and aromatic groups may result in a less rigid polymer and mayalso result in the material becoming colored, which is disadvantageousfor applications such as corrective lenses.

In some embodiments, R₃ is an organic linking group that may be analkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl,substituted alkynyl, aryl, or substituted aryl further comprising ahetero atom. In some embodiments, the hetero atom is preferably a maingroup element selected from the group consisting of S, P, As, Se, Ge,Sn, In, Eb, Te.

In some embodiments, R₃ is an organic linking group that may be analkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl,substituted alkynyl, aryl, or substituted aryl further comprising ahetero atom. In some embodiments, the hetero atom is preferably atransition metal element selected from the group consisting of Mn, FeCo, Ni and second and third row transition metals such as, but notexclusively, Ru, Rh, Re, Os, Zr, etc.

In structure (I), YY may have a value of 0, 1, or 2. In embodimentswherein YY has a value of 0, the R₃ organic linking moiety is bonded totwo X main group elements. In embodiments wherein YY has a value of 1,the R₃ organic linking moiety is bonded to three X main group elements.In embodiments wherein YY has a value of 2, the R₃ organic linkingmoiety is bonded to four X main group elements. In preferredembodiments, the value of YY is 0.

In some preferred embodiments, M is bonded to four substituents as shownin Structure (I). In some embodiments, M is a main group element or atransition metal capable of forming a tetravalent coordination sphere.In some embodiments, M is an organic moiety bonded to four substituents.In a preferred embodiment, the value of Y in Structure (I) is 4, and theR₂ moiety is not present in the polymer generally depicted by Structure(I). In a preferred embodiment, the value of Z is 2 in Structure (I). Ina preferred embodiment, the R₃ linking moiety is bonded to two X maingroup elements, i.e., the value of YY is 0. Such a polymer can begenerally depicted by the following structure (IIa):

wherein M, R₁, X, and R₃ are as defined in connection with Structure(I).

In some preferred embodiments, the value of Y is 4, the value of Z is 2,R₁ is a direct bond between M and the ethylene group depicted betweenthe M and the X, and the R₃ linking moiety is bonded to two X main groupelements, i.e., the value of YY is 0. Such a polymer can be generallydepicted by the following structure (IIb):

wherein M, X, and R₃ are as defined in connection with Structure (I).The polymer having structure (IIb) can be depicted alternatively asStructure (XXV) in which M is depicted in the center of the repeat unit:

In some preferred embodiments, the value of Y is 4, the value of Z is 2,R₁ is a methylene linking group, and the R₃ linking moiety is bonded totwo X main group elements, i.e., the value of YY is 0. Such a polymercan be generally depicted by the following structure (IIc):

wherein M, X, and R₃ are as defined in connection with Structure (I).The polymer having structure (IIC) can be depicted alternatively asStructure (XXVI) in which M is depicted in the center of the repeatunit:

In some preferred embodiments, M is bonded to three substituents asshown in Structure (I). In some embodiments, M is a main group elementor a transition metal capable of forming a trivalent coordinationsphere. In some embodiments, M is an organic moiety bonded to threesubstituents. In a preferred embodiment, the value of Y is 4 (R₂ moietyis not present in the polymer generally depicted by Structure (I)), andthe value of Z is 1 in Structure (I). In a preferred embodiment, the R₃linking moiety is bonded to two X main group elements, i.e., the valueof YY is 0. Such a polymer can be generally depicted by the followingstructure (IIIa):

wherein M, R₁, X, and R₃ are as defined in connection with Structure(I).

In some preferred embodiments, Y is 4 (R₂ moiety is not present in thepolymer generally depicted by Structure (I)), Z is 1 in Structure (I),R₁ is a direct bond between M and the ethylene group depicted betweenthe M and the X, and the R₃ linking moiety is bonded to two X main groupelements, i.e., the value of YY is 0. Such a polymer can be generallydepicted by the following structure (IIIb):

wherein M, X, and R₃ are as defined in connection with Structure (I).The polymer having structure (IIIb) can be depicted alternatively asStructure (XXVII) in which M is depicted in the center of the repeatunit:

In some preferred embodiments, Y is 4 (R₂ moiety is not present in thepolymer generally depicted by Structure (I)), Z is 1 in Structure (I),R₁ is a methylene linking group, and the R₃ linking moiety is bonded totwo X main group elements, i.e., the value of YY is 0. Such a polymercan be generally depicted by the following structure (IIIc):

wherein M, X, and R₃ are as defined in connection with Structure (I).The polymer having structure (IIIc) can be depicted alternatively asStructure (XXVIII) in which M is depicted in the center of the repeatunit:

In some preferred embodiments, M is Si. The Si atom has a tetravalentcoordination sphere. R₁ is a direct bond between M and the ethylenegroup depicted between the M and the X; X is a sulfur atom; and R₃ is ahydrocarbyl having from two to five carbon atoms, e.g., a linear chainof 2, 3, 4, or 5 —CH₂— moieties. This polymer may be depicted below asStructure (IVa):

In one preferred embodiment, R₃ is a hydrocarbyl having two carbonatoms. In one preferred embodiment, R₃ is a hydrocarbyl having fivecarbon atoms.

In some preferred embodiments, M is Ge. The Ge atom has a tetravalentcoordination sphere. R₁ is a direct bond between M and the ethylenegroup depicted between the M and the X; X is a sulfur atom; and R₃ is ahydrocarbyl having from two to five carbon atoms, e.g., a linear chainof 2, 3, 4, or 5 —CH₂— moieties. This polymer may be depicted below asStructure (IVb):

In one preferred embodiment, R₃ is a hydrocarbyl having two carbonatoms. In one preferred embodiment, R₃ is a hydrocarbyl having fivecarbon atoms.

In some preferred embodiments, M is Si. The Si atom has a tetravalentcoordination sphere. R₁ is a direct bond between M and the ethylenegroup depicted between the M and the X; X is a sulfur atom; and R₃ is anaryl group having from 6 to 14 carbon atoms, e.g., phenyl, naphthenyl.This polymer may be depicted below as Structure (IVc):

Preferably, R₃ is an aryl group having 6 carbon atoms, e.g., phenyl.

In some preferred embodiments, M is Ge. The Ge atom has a tetravalentcoordination sphere. R₁ is a direct bond between M and the ethylenegroup depicted between the M and the X; X is a sulfur atom; and R₃ is anaryl group having from 6 to 14 carbon atoms, e.g., phenyl, naphthenyl.This polymer may be depicted below as Structure (IVd):

Preferably, R₃ is an aryl group having 6 carbon atoms, e.g., phenyl.

In some preferred embodiments, M is Si. The Si atom has a tetravalentcoordination sphere. R₁ is a methylene linking moiety; X is a sulfuratom; and R₃ is a hydrocarbyl having from two to five carbon atoms,e.g., a linear chain of 2, 3, 4, or 5 —CH₂— moieties. This polymer maybe depicted below as Structure (IVe):

In one preferred embodiment, R₃ is a hydrocarbyl having two carbonatoms. In one preferred embodiment, R₃ is a hydrocarbyl having fivecarbon atoms.

In some preferred embodiments, M is Ge. The Ge atom has a tetravalentcoordination sphere. R₁ is a methylene linking moiety; X is a sulfuratom; and R₃ is a hydrocarbyl having from two to five carbon atoms,e.g., a linear chain of 2, 3, 4, or 5 —CH₂— moieties. This polymer maybe depicted below as Structure (IVf):

In one preferred embodiment, R₃ is a hydrocarbyl having two carbonatoms. In one preferred embodiment, R₃ is a hydrocarbyl having fivecarbon atoms.

In some preferred embodiments, M is Si. The Si atom has a tetravalentcoordination sphere. R₁ is a methylene linking moiety; X is a sulfuratom; and R₃ is an aryl group having from 6 to 14 carbon atoms, e.g.,phenyl, naphthenyl. This polymer may be depicted below as Structure(IVg):

Preferably, R₃ is an aryl group having 6 carbon atoms, e.g., phenyl.

In some preferred embodiments, M is Ge. The Ge atom has a tetravalentcoordination sphere. R₁ is a methylene linking moiety; X is a sulfuratom; and R₃ is an aryl group having from 6 to 14 carbon atoms, e.g.,phenyl, naphthenyl. This polymer may be depicted below as Structure(IVh):

Preferably, R₃ is an aryl group having 6 carbon atoms, e.g., phenyl.

In some embodiments, M is an organic moiety comprising three substituentgroups; R₁ is a direct bond between M and the ethylene group depictedbetween the M and the X; X is a sulfur atom; and R₃ is a hydrocarbylhaving from two to five carbon atoms, e.g., a linear chain of 2, 3, 4,or 5 —CH₂— moieties. This polymer may be depicted below as Structure(IVi):

In one preferred embodiment, R₃ is a hydrocarbyl having two carbonatoms. In one preferred embodiment, R₃ is a hydrocarbyl having fivecarbon atoms.

In some preferred embodiments, the polymer has the following structure(IVj):

wherein the N₁, N₂, N₃, N₄, N₅, and N₆ may be carbon atoms or they maybe heteroatoms selected from among main group elements or transitionmetal elements, e.g., N, O, S, Se, Sb, P, Ge, Sn, Te, Ga, In, Ni, Co,Ti, Zr, and W. In some embodiments at least three of the N₁, N₂, N₃, N₄,N₅, and N₆ are carbon atoms, and the remaining three or fewer of the N₁,N₂, N₃, N₄, N₅, and N₆ may be a heteroatom, such as N or S. In somepreferred embodiments, three of the N₁, N₂, N₃, N₄, N₅, and N₆ arecarbon atoms and the remaining three of the N₁, N₂, N₃, N₄, N₅, and N₆are nitrogen atoms. In some preferred embodiments, three of the N₁, N₂,N₃, N₄, N₅, and N₆ are carbon atoms and the remaining three of the N₁,N₂, N₃, N₄, N₅, and N₆ are sulfur atoms. Each R may be hydrogen, ahydrocarbyl having from 1 to 3 carbon atoms or a heteroatom, such as O,N, or S.

In some preferred embodiments, M is an organic moiety comprising threesubstituent groups; R₁ is a methylene linking moiety; X is a sulfuratom; and R₃ is a hydrocarbyl having from two to five carbon atoms,e.g., a linear chain of 2, 3, 4, or 5 —CH₂— moieties. This polymer maybe depicted below as Structure (IVk):

In one preferred embodiment, R₃ is a hydrocarbyl having two carbonatoms. In one preferred embodiment, R₃ is a hydrocarbyl having fivecarbon atoms.

In a preferred embodiment, the polymer has the following structure(IV1):

wherein the N₁, N₂, N₃, N₄, N₅, and N₆ may be carbon atoms or they maybe heteroatoms selected from among main group elements or transitionmetal elements, e.g., N, O, S, Se, Sb, P, Ge, Sn, Te, Ga, In, Ni, Co,Ti, Zr, and W. In some embodiments at least three of the N₁, N₂, N₃, N₄,N₅, and N₆ are carbon atoms, and the remaining three or fewer of the N₁,N₂, N₃, N₄, N₅, and N₆ may be a heteroatom, such as N or S. In somepreferred embodiments, three of the N₁, N₂, N₃, N₄, N₅, and N₆ arecarbon atoms and the remaining three of the N₁, N₂, N₃, N₄, N₅, and N₆are nitrogen atoms. In some preferred embodiments, three of the N₁, N₂,N₃, N₄, N₅, and N₆ are carbon atoms and the remaining three of the N₁,N₂, N₃, N₄, N₅, and N₆ are sulfur atoms. Each R may be hydrogen, ahydrocarbyl having from 1 to 3 carbon atoms or a heteroatom, such as O,N, or S.

In some embodiments, M is an organic moiety comprising three substituentgroups; R₁ is a direct bond between M and the ethylene group depictedbetween the M and the X; X is a sulfur atom; and R₃ is an aryl grouphaving from 6 to 14 carbon atoms, e.g., phenyl, naphthenyl. This polymermay be depicted below as Structure (IVm):

Preferably, R₃ is an aryl group having 6 carbon atoms, e.g., phenyl.

In a preferred embodiment, the polymer has the following structure(IVn):

wherein the N₁, N₂, N₃, N₄, N₅, and N₆ may be carbon atoms or they maybe heteroatoms selected from among main group elements or transitionmetal elements, e.g., N, O, S, Se, Sb, P, Ge, Sn, Te, Ga, In, Ni, Co,Ti, Zr, and W. In some embodiments at least three of the N₁, N₂, N₃, N₄,N₅, and N₆ are carbon atoms, and the remaining three or fewer of the N₁,N₂, N₃, N₄, N₅, and N₆ may be a heteroatom, such as N or S. In somepreferred embodiments, three of the N₁, N₂, N₃, N₄, N₅, and N₆ arecarbon atoms and the remaining three of the N₁, N₂, N₃, N₄, N₅, and N₆are nitrogen atoms. In some preferred embodiments, three of the N₁, N₂,N₃, N₄, N₅, and N₆ are carbon atoms and the remaining three of the N₁,N₂, N₃, N₄, N₅, and N₆ are sulfur atoms. Each R may be hydrogen, ahydrocarbyl having from 1 to 3 carbon atoms or a heteroatom, such as O,N, or S.

In some embodiments, M is an organic moiety comprising three substituentgroups; R₁ is a methylene linking moiety; X is a sulfur atom; and R₃ isan aryl group having from 6 to 14 carbon atoms, e.g., phenyl,naphthenyl. This polymer may be depicted below as Structure (IVo):

Preferably, R₃ is an aryl group having 6 carbon atoms, e.g., phenyl.

In a preferred embodiment, the polymer has the following structure(IVp):

wherein the N₁, N₂, N₃, N₄, N₅, and N₆ may be carbon atoms or they maybe heteroatoms selected from among main group elements or transitionmetal elements, e.g., N, O, S, Se, Sb, P, Ge, Sn, Te, Ga, In, Ni, Co,Ti, Zr, and W. In some embodiments at least three of the N₁, N₂, N₃, N₄,N₅, and N₆ are carbon atoms, and the remaining three or fewer of the N₁,N₂, N₃, N₄, N₅, and N₆ may be a heteroatom, such as N or S. In somepreferred embodiments, three of the N₁, N₂, N₃, N₄, N₅, and N₆ arecarbon atoms and the remaining three of the N₁, N₂, N₃, N₄, N₅, and N₆are nitrogen atoms. In some preferred embodiments, three of the N₁, N₂,N₃, N₄, N₅, and N₆ are carbon atoms and the remaining three of the N₁,N₂, N₃, N₄, N₅, and N₆ are sulfur atoms. Each R may be hydrogen, ahydrocarbyl having from 1 to 3 carbon atoms or a heteroatom, such as O,N, or S.

In one preferred embodiment, M is derived from1,3,5-Triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione; R₁ is a methylenelinking moiety; X is a sulfur atom; and R₃ is an aryl group having from6 carbon atoms. This polymer may be depicted below as Structure (IVq):

The cross-linked polymers that may be depicted by general structures (I)through (IVq) are obtained by the reaction between a firstmultifunctional monomer comprising alkenyl groups, e.g., vinyl groups orallyl groups, and a second multifunctional monomer comprising moietiesthat are reactive with alkenyl groups. The reaction between amultifunctional monomer comprising alkenyl and a multifunctional monomercomprising moieties that are reactive with alkenyl yields a large degreeof cross-linking in the resultant, which may impart excellent mechanicalproperties, such as hardness, fracture resistance, and scratchresistance.

The first multifunctional monomer comprises alkenyl moieties, e.g.,vinyl groups or allyl groups. The first multifunctional monomer has thegeneral structure (V):

In some embodiments, M is a main group element or a transition metal,the main group element or transition metal element being capable ofachieving a coordination number of 3, 4, 5, or 6. At least twosubstituent moieties in the coordination sphere comprise alkenyl groups.In Structure (V), M is a moiety bonded to at least two alkenyl groups,e.g., vinyl groups, allyl groups, and the like, such as between two andsix alkenyl groups. In preferred embodiments, M is bonded to three orfour substituents comprising alkenyl groups, e.g., three or four vinylgroups or three or four allyl groups.

In some embodiments, in Structure (V), M is a main group element capableof achieving a coordination number of 3 (forming a trivalentcoordination sphere). In some embodiments, M is a main group elementcapable of achieving a coordination number of 4 (forming a tetravalentcoordination sphere). The main group element capable of forming atrivalent or tetravalent coordination sphere is a second, third, orfourth row main group element having an electronegativity less than 2.65(Pauling scale). In some preferred embodiments, the main group elementsmay be selected from among Si, Ge, or Sn.

In some embodiments, in Structure (V), M is a transition metal elementcapable of achieving a coordination number of 3 (forming a trivalentcoordination sphere). In some embodiments, M is a transition metalelement capable of achieving a coordination number of 4 (forming atetravalent coordination sphere). In some preferred embodiments, thetransition metal may be selected from among Mn, Zr, Ti, and Cr.

In some embodiments, M is an organic moiety comprising at least twoalkenyl groups, such as two alkenyl, three alkenyl, four alkenyl, fivealkenyl, six alkenyl, and preferably three or four alkenyl groups.Herein, organic moiety generally refers to a moiety comprising elementscommonly found in biological compounds, such as C, H, O, N, S, and P. Inpreferred embodiments, the moiety comprises only C, H, O, N, S, or P.However, some moieties that are considered “organic” can additionallycomprise additional heteroatoms, such as Se, Sb, P, Ge, Sn, Te, Ga, In,Ni, Co, Ti, Zr, and W. The nomenclature “organic” is used herein todifferentiate these types of carbon-based M moieties compared to the Mmoieties comprising main group elements and transition metal elements. Mcan be an alkyl, which may be linear, branched or cyclic, having bondedthereto the at least two alkenyl groups. M can be an aromatic group,having bonded thereto the at least two alkenyl groups. The organicmoiety may contain one or more heteroatoms selected from the main groupof elements including but not exclusively N, O, S, Se, Sb, P, Ge, Sn,Te, Ga, and In. The organic moiety may contain one or more transitionelement atoms selected from among, but not limited to, Ni, Co, Ti, Zr,and W.

In some embodiments, the organic moiety has the basic ring structureshown below, in which at least two alkenyl groups are bonded thereto.The N₁, N₂, N₃, N₄, N₅, and N₆ may be carbon atoms or they may beheteroatoms selected from among main group elements or transition metalelements, e.g., N, O, S, Se, Sb, P, Ge, Sn, Te, Ga, In, Ni, Co, Ti, Zr,and W. The alkenyl containing moiety may be bonded to a carbon atom onthe ring structure of to any of the N₁, N₂, and N₃. The ring structuresmay be aromatic or non-aromatic.

In some embodiments at least three of the N₁, N₂, N₃, N₄, N₅, and N₆ arecarbon atoms, and the remaining three or fewer of the N₁, N₂, N₃, N₄,N₅, and N₆ may be a heteroatom, such as N or S. In some preferredembodiments, three of the N₁, N₂, N₃, N₄, N₅, and N₆ are carbon atomsand the remaining three of the N₁, N₂, N₃, N₄, N₅, and N₆ are nitrogenatoms. In some preferred embodiments, three of the N₁, N₂, N₃, N₄, N₅,and N₆ are carbon atoms and the remaining three of the N₁, N₂, N₃, N₄,N₅, and N₆ are sulfur atoms. In some preferred embodiments, the organicmoiety having any of the above ring structures has one of the followingstructures:

In some embodiments, the organic moiety can be aromatic any may comprisefive- and six-member rings, which may be fused or unfused and havingbonded thereto substituents comprising the at least two alkenyl groups.Exemplary such aromatic groups include benzene, naphthalene,cyclopentadiene, anthracene, phenanthrene, and 1H-indene. These ringsthemselves may contain heteroatoms in place of carbon at one or moreapexes, the heteroatoms selected from among the main group andtransition metals, e.g., N, O, S, Se, Sb, P, Ge, Sn, Te, Ga, In, Ni, Co,Ti, Zr, and W.

In Structure (V), Y and Z are values that dictate the number of ligandsthat form a coordination sphere around the central M main group elementor transition metal or the number of substituents covalently bonded tothe organic M moiety. In Structure (V), Y may be 0, 1, 2, 3 or 4. InStructure (V), Z may be 0, 1, 2, 3, or 4. The values of Y and Z definethe number of alkenyl moieties bonded to M. For example, when M is atransition metal or main group element, the values of Y and Z may besuch that the total number of moieties bonded to M is 3 (i.e., M forms atrivalent coordination sphere) or 4 (i.e., M forms a tetravalentcoordination sphere).

Z may be 0, 1, 2, 3 or 4 such that the first multifunctional monomercomprising alkenyl, e.g., vinyl or allyl, may comprise 2, 3, 4, 5 or 6alkenyl functional groups. In preferred embodiments, Z is 1 or 2. Thealkenyl groups, e.g., vinyl or allyl groups, may be directly bonded tothe main group element, the transition metal, or the organic moiety orthey may be linked to the main group element or the transition metal viahydrocarbyl having from 1 to about 9 carbons, such as alkyl groups(methylene, ethylene, n-propylene, isopropylene, n-butylene,sec-butylene, isobutylene, tert-butylene, pentylene, neopentylene,hexylenes, heptylenes, octylene, nonylene) or aryl groups (phenyl,benzyl, xylyl, mesityl).

Y may be 0, 1, 2, 3, or 4 such that the first multifunctional monomermay comprise 4, 3, 2, 1 or 0 non-functional moieties, i.e., hydrocarbylhaving from 1 to about 9 carbons, such as alkyl groups (methyl, ethyl,n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, pentyl,neopentyl, hexyl, heptyl, octyl, nonyl) or aryl groups (phenyl, benzyl,xylyl, mesityl). In the context of the present invention, non-functionalmoieties such as alkyl groups and aryl groups are non-reactive with thesecond multifunctional monomer. In preferred embodiments, Y is 4.

In some preferred embodiments, the values of Y and Z are such that thefirst multifunctional monomer comprising alkenyl, e.g., vinyl or allyl,comprises 3 or 4 ligands or covalently bonded moieties. Combinationswithin the scope of the present invention include, but are not limitedto, four ligands or covalently bonded moieties all of which comprisealkenyl, e.g., four vinyl or allyl moieties; three ligands or covalentlybonded moieties comprising alkenyl, e.g., three vinyl or allyl moietiesand 0 or 1 moiety not comprising alkenyl; and two ligands or covalentlybonded moieties comprising alkenyl, e.g., two vinyl or allyl moieties,and 0, 1, or 2 moieties not comprising alkenyl. The non-functionalmoieties and linking moieties may be substituted, but are preferably notsubstituted.

In Structure (V), R₁ is, independently of any other R₁ in themultifunctional monomer, a direct bond between M and the alkenyl group,e.g., a vinyl group, or a hydrocarbyl linking moiety having between 1and 9 carbon atoms, e.g., an allyl group. Generally, the two, three,four, five, or six R₁ groups are the same. In some preferredembodiments, each R₁ group is a direct bond between M and the alkenylgroup, such that the alkenyl group is a vinyl group. In someembodiments, each R₁ group is a hydrocarbyl linking moiety havingbetween 1 and 4 carbon atoms, such as methylene, ethylene, n-propylene,iso-propylene, n-butylene, iso-butylene, and tert-butylene. In somepreferred embodiments, R₁ is methylene, such that the alkenyl group isan allyl group.

In Structure (V), R₂ is, independently of any other R₂ in themultifunctional monomer, a hydrocarbyl moiety having between 1 and about9 carbon atoms. In general, if two R₂ groups are present in themultifunctional monomer whose structure is generally depicted asstructure (II), they are the same. Preferably, the multifunctionalmonomer whose structure is generally depicted as structure (II) does notcomprise any R₂ groups.

In some preferred embodiments, the value of Y is 4, and the value of Zis 2 in Structure (V). That is, the first multifunctional monomercomprising alkenyl, e.g., vinyl or allyl groups, having the generalstructure (V) comprises no R₂ groups and comprises 4 ligands orcovalently bonded moieties comprising alkenyl, e.g., vinyl or allylgroups. Such a first multifunctional monomer has the following generalstructure (VIa):

wherein M and R₁ are as defined above in connection with Structure (V).

In some preferred embodiments, the value of Y is 4, and the value of Zis 1 in Structure (V). That is, the first multifunctional monomercomprising alkenyl moieties, e.g., vinyl groups, allyl groups and thelike having the general structure (V) comprises no R₂ groups andcomprises three ligands or covalently bonded moieties comprising alkenylgroups, e.g., vinyl or allyl. Such a first multifunctional monomer hasthe following general structure (VIb):

wherein M and R₁ are as defined above in connection with Structure (V).

In some preferred embodiments, the first multifunctional monomer ofStructure (VIb) comprises an organic moiety and has the followinggeneral structure (VIc):

wherein R₁ are as defined above in connection with Structure (V), theN₁, N₂, N₃, N₄, N₅, and N₆ may be carbon atoms or they may beheteroatoms selected from among main group elements or transition metalelements, e.g., N, O, S, Se, Sb, P, Ge, Sn, Te, Ga, In, Ni, Co, Ti, Zr,and W. In some embodiments at least three of the N₁, N₂, N₃, N₄, N₅, andN₆ are carbon atoms, and the remaining three or fewer of the N₁, N₂, N₃,N₄, N₅, and N₆ may be a heteroatom, such as N or S. In some preferredembodiments, three of the N₁, N₂, N₃, N₄, N₅, and N₆ are carbon atomsand the remaining three of the N₁, N₂, N₃, N₄, N₅, and N₆ are nitrogenatoms. In some preferred embodiments, three of the N₁, N₂, N₃, N₄, N₅,and N₆ are carbon atoms and the remaining three of the N₁, N₂, N₃, N₄,N₅, and N₆ are sulfur atoms. Each R may be hydrogen, a hydrocarbylhaving from 1 to 3 carbon atoms or a heteroatom, such as O, N, or S.

In preferred embodiments, the non-functional moieties and linkingmoieties are not substituted with any moiety comprising an atom havingan electronegativity greater than 2.65 (Pauling scale) such as oxygen,nitrogen, fluorine, chlorine, and the like, although such atoms are notexcluded from the first multifunctional monomer.

In some embodiments, the value of Y is 4, R₁ is a direct bond between Mand a vinyl group, and the value of Z is 2 in the first multifunctionalmonomer of general structure (V). Such a monomer has the generalstructure (VII):

wherein M is defined above in connection with Structure (V).

In some embodiments, the value of Y is 4, R₁ is a direct bond between Mand a vinyl group, and the value of Z is 1 in the first multifunctionalmonomer of general structure (V). Such a monomer has the generalstructure (VIII):

wherein M is defined above in connection with Structure (V).

In some embodiments, the value of Y is 3, R₁ is a direct bond between Mand a vinyl group, and the value of Z is 1 in the first multifunctionalmonomer of general structure (V). Such a monomer has the generalstructure (IX):

wherein M and R₂ are defined above in connection with Structure (V).

In some embodiments, the value of Y is 2, R₁ is a direct bond between Mand the vinyl group, and the value of Z is 0 in the firstmultifunctional monomer of general structure (V). Such a monomer has thegeneral structure (X):

wherein M and R₂ are defined above in connection with Structure (V).

In a preferred embodiment, the first multifunctional monomer is that ofgeneral structure (VII), and M is Si. Herein, the first multifunctionalmonomer comprises four vinyl groups directly bonded to Si. This firstmultifunctional monomer, tetravinylsilane, has the following structure(XI):

In a preferred embodiment, the first multifunctional monomer is that ofgeneral structure (VII), and M is Ge. Herein, the first multifunctionalmonomer comprises four vinyl groups directly bonded to Ge. This firstmultifunctional monomer, tetravinylgermane, has the following structure(XII):

In some preferred embodiments, M may be the cyclic structure oftriethenyl. For example, in a preferred embodiment, the firstmultifunctional monomer is that of general structure (VIII), and M is1,3,5-triazinane-2,4,6-trione. The vinyl groups are bonded to eachnitrogen atom. This first multifunctional monomer,1,3,5-trivinyl-1,3,5-triazinane-2,4,6-trione, has the followingstructure (XIII):

In another embodiment wherein M is the cyclic structure of triethenyl,the multifunctional monomer is 2,4,6-trivinyl-1,3,5-trithiane, havingthe following structure (XIV):

In some embodiments, the value of Y is 4, R₁ is a methylene linkinggroup between M and the vinyl group (i.e., is an allyl moiety), and thevalue of Z is 2 in the first multifunctional monomer comprising vinyl ofgeneral structure (V). Such a monomer has the general structure (XV):

wherein M is defined above in connection with Structure (V).

In some embodiments, the value of Y is 4, R₁ is a methylene linkinggroup between M and the vinyl group (i.e., is an allyl moiety), and thevalue of Z is 1 in the first multifunctional monomer comprising vinyl ofgeneral structure (V). Such a monomer has the general structure (XVI):

wherein M is defined above in connection with Structure (V).

In some embodiments, the value of Y is 3, R₁ is a methylene linkinggroup between M and the vinyl group (i.e., is an allyl moiety), and thevalue of Z is 1 in the first multifunctional monomer comprising vinyl ofgeneral structure (V). Such a monomer has the general structure (XVII):

wherein M and R₂ are defined above in connection with Structure (V).

In some embodiments, the value of Y is 2, R₁ is a methylene linkinggroup between M and the vinyl group (i.e., is an allyl moiety), and thevalue of Z is 0 in the first multifunctional monomer comprising vinyl ofgeneral structure (V). Such a monomer has the general structure (XVIII):

wherein M and R₂ are defined above in connection with Structure (V).

In a preferred embodiment, the first multifunctional monomer comprisingvinyl is that of general structure (XV), and M is Si. Herein, the firstmultifunctional monomer comprising vinyl comprises four vinyl groupsbonded to Si via a linking methylene group, i.e., is an allyl moiety.This first multifunctional monomer, tetraallylsilane, has the followingstructure (XIX):

In a preferred embodiment, the first multifunctional monomer comprisingvinyl is that of general structure (XV), and M is Ge. Herein, the firstmultifunctional monomer comprising vinyl comprises four vinyl groupsbonded to Ge via a linking methylene group, i.e., is an allyl moiety.This first multifunctional monomer, tetraallylgermane, has the followingstructure (XX):

In a preferred embodiment, the first multifunctional monomer is that ofgeneral structure (VIII), and M is 1,3,5-triazinane-2,4,6-trione.Herein, the first multifunctional monomer comprises four vinyl groupsbonded to 1,3,5-triazinane-2,4,6-trione via a linking methylene group,i.e., is an allyl moiety. This first multifunctional monomer,1,3,5-triallyl-1,3,5-triazinane-2,4,6-trione, has the followingstructure (XXI):

In another embodiment wherein M is the cyclic structure of triethenyland further comprising a methylene linking moiety, the multifunctionalmonomer is 2,4,6-triallyl-1,3,5-trithiane, having the followingstructure (XXII):

The second multifunctional monomer comprises moieties that are reactivewith vinyl. In order to achieve a high degree of cross-linking, thesecond multifunctional monomer comprises at least two moieties that arereactive with alkenyl such as two, three, four or more reactivemoieties. Reactive moieties include any element whose functional group—XH undergoes a cross-linking reaction with vinyl. In general, thesecond multifunctional monomer comprising multiple reactive moietieslinks the reactive moieties through a hydrocarbyl linking group, e.g.,alkyl, alkenyl, alkynyl, or aryl that may or may not be substituted,e.g., with a heteroatom. Preferably, the second multifunctional monomeris such that atoms having an electronegativity greater than 2.65(Pauling scale) such as oxygen, nitrogen, fluorine, chlorine, and thelike is limited. Even more preferably, atoms having an electronegativitygreater than 2.65 (Pauling scale) such as oxygen, nitrogen, fluorine,chlorine, and the like are excluded from the second multifunctionalmonomer.

In some embodiments, a second multifunctional monomer comprisingmoieties reactive with vinyl groups may have the general structure(XXIII):R₃—((XH)_(2+YY)   Structure (XXIII)

In Structure (XXIII), X is an element whose functional group —XH isreactive with vinyl groups. X may be a main group element selected fromamong S, P, As, Se, Te, and Sb. In some preferred embodiments, X isselected from among S, Se, or Te. In some preferred embodiments, X is S,and the polymer of the present invention is prepared by thiol-enecoupling.

In Structure (XXIII), YY is an integer having a value of 0, 1, or 2. Theequation 2+YY defines the number of —XH reactive moieties bonded to theR₃ organic linking groups. In some preferred embodiments, YY is 0, suchthat the second multifunctional monomer comprises two —XH reactivemoieties.

In Structure (XXIII), R₃ is an organic linking group that links the —XHreactive groups. R₃ may be alkyl, substituted alkyl, alkenyl,substituted alkenyl, alkynyl, substituted alkynyl, aryl, or substitutedaryl. Alkyl R₃ linking groups generally have between 1 and about 10carbon atoms, preferably between 1 and 5 carbon atoms. With regard toalkenyl, alkynyl, and aryl linking groups, the number of carbon atomsmay be greater, such as between 2 and about 24 carbon atoms, preferablybetween 2 and about 20 carbon atoms, more preferably between 2 and about12 carbon atoms. The use of alkenyl, alkynyl, and aryl linking groups isparticularly advantageous since these linking groups incorporateunsaturated bonds into to the cross-linked polymer, which has been foundto increase the refractive index of the resultant material. This effectis particularly achieved when the linking group incorporates conjugateddouble and triple bonds into the resultant material. Linking groupscomprising conjugated doubled and triple bonds include alkenyl, alkynyl,or aryl in which the number of conjugated double bonds is between 2 andabout 10, preferably between 2 and about 5. A high number of conjugateddouble bonds and aromatic groups may result in a less rigid polymer andmay also result in the material becoming colored, which isdisadvantageous for applications such as corrective lenses.

In some embodiments, R₃ is an organic linking group that may be analkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl,substituted alkynyl, aryl, or substituted aryl further comprising ahetero atom, preferably a main group element selected from the groupconsisting of S, P, As, Se, Ge, Sn, In, Sb, Te.

In some embodiments, R3 is an organic linking group that may be analkyl, substituted alkyl, alkenyl, substituted alkenyl, alkynyl,substituted alkynyl, aryl, or substituted aryl further comprising ahetero atom, preferably a transition metal element selected from thegroup consisting of Mn, Fe Co, Ni and second and third row transitionmetals such as, but not exclusively, Ru, Rh, Re, Os, Zr etc.

The structures of several R₃ groups containing no heteroatoms are asfollows:

The R₃ group may include heteroatoms of main group elements andtransition metal elements. Inclusion of such heteroatoms in the R₃ groupthat may further enhance the refractive index.

Representative examples of R₃ linking groups containing heteroatoms areshown below include two coordinate structures where M′ are main groupelements, typically, but not exclusively S, Se, Te. The structures canbe linear or ring structures, saturated or unsaturated, containing oneor more of the elements M′, where M′ may be all the same element or amixture of elements. Exemplary such R₃ groups containing M′ heteroatomsmay have the general structure shown below:

R₃ can contain three coordinate structures with M″ being from the maingroup, primarily but not exclusively P, As, Sb, Bi. Exemplary such R₃groups containing M″ heteroatoms are shown below:

R₃ can contain four-coordinate structures where M′″ is a main groupelement including, but not limited to Si, Ge, Sn or transition metalssuch as, but not limited to Co, Ni, Fe. Exemplary such R₃ groupscontaining M′″ heteroatoms are shown below:

R₃ can contain 6 coordinate structures where M″″ can be a transitionmetal including but not limited to Mo, Ru, Fe, or Re. Exemplary such R₃groups containing M″″ heteroatoms are shown below:

In each of the general R₃ linking groups structures, n is between 1 andabout 10. In each of the above exemplary R₃ linking groups structures,the R groups are hydrocarbyl substituents having from 1 to about 8carbon atoms, preferably 1 to 3 carbon atoms, or hydrogen.

Each of the R₃ linking groups may be substituted with moietiescomprising heteroatoms. Preferably, any such substituents have a limitedproportion of atoms having an electronegativity greater than 2.65(Pauling scale) such as oxygen, nitrogen, fluorine, chlorine, and thelike. Even more preferably, the substituents lack atoms having anelectronegativity greater than 2.65 (Pauling scale) such as oxygen,nitrogen, fluorine, chlorine, and the like.

In one preferred embodiment, the second multifunctional monomercomprising moieties reactive with vinyl groups is difunctional, i.e., YYis 0 and the second multifunction monomer comprises two moietiesreactive with vinyl groups. A difunctional monomer comprising tworeactive moieties may have the general structure (XXIV):HX—R₃—XH   Structure (XXIV)

In structure (XXIV), R₃ and X are as defined above in connection withgeneral structure (XXIII).

Exemplary second multifunctional monomers in which X is sulfur atom,include, for example, ethane-1,2-dithiol; propane-1,2-dithiol;propane-1,3-dithiol; butane-1,2-dithiol; butane-1,3-dithiol;butane-2,3-dithiol; butane-1,4-dithiol; pentane-1,3-dithiol,pentane-1,4-dithiol, pentane-1,5-dithiol, pentane-2,3-dithiol, andpentane-2,4-dithiol; hexane-1,6-dithiol and other hexanedithiols;heptane-1,7-dithiol and other heptanedithiols; octane-1,8-dithiol andother octanedithiols; 2,2′-oxydiethanethiol;3,6-dioxa-1,8-octanedithiol; ethylene glycol bisthiol-glycolate;dl-1,4-dithiothreitol; 2,2′-thiodiethanethiol;bis(2-mercaptoethyl)sulphone; 2,5-dimercapto-1,3,4-thiadiazole;5-({2-[(5-mercapto-1,3,4-thiadiazol-2-yl)thio]ethyl}thio)-1,3,4-thiadiazole-2-thiol;pentaerythritol tetra(2-mercaptoacetate); trimethylolpropanetris(3-mercaptopropionate); trimethylolpropane tris(2-mercaptoacetate);benzene-1,2-dithiol; benzene-1,3-dithiol; benzene-1,4-dithiol;3,4-dimercaptotoluene; 1,4-benzenedimethanethiol;1,3-benzenedimethanethiol; 1,6-di(methanethiol)-3,4-dimethyl-phenyl;[3-(mercaptomethyl)-2,4,6-trimethylphenyl]methanethiol;1,5-dimercaptonaphthalene;3,3′-thiobis[2-[(2-mercaptoethyl)thio]-1-propanethiol;5-[3-(5-mercapto-1,3,4-oxadiazole-2-yl)propyl]-1,3,4-oxadiazole-2-thiol;1,3,5-triazine-2,4,6(1H, 3H,5H)-trithione; and2,3-bis[(2-mercaptoethyl)thio]-1-propanethiol.

In one preferred embodiment, X is S, and R₃ is an ethyl group, and themultifunctional monomer comprising moieties reactive with vinyl groupsis a difunctional molecule. Such a monomer is ethane-1,2-dithiol.

In one preferred embodiment, X is S, and R₃ is a pentyl group, and themultifunctional monomer comprising moieties reactive with vinyl groupsis a difunctional molecule. Such monomers include pentane-1,3-dithiol,pentane-1,4-dithiol, pentane-1,5-dithiol, pentane-2,3-dithiol, andpentane-2,4-dithiol. A preferred monomer is pentane-1,5-dithiol.

In one preferred embodiment, X is S, and R₃ is a phenyl group, and themonomer is a difunctional monomer. Such monomers includebenzene-1,2-dithiol, benzene-1,3-dithiol, and benzene-1,4-dithiol. Apreferred monomer is benzene-1,3-dithiol.

The present invention is additionally directed to a method of forming ahigh refractive index material comprising a polymer having a high degreeof cross-linking and containing polarizable elements.

In some embodiments, the method of the present invention comprisescontacting the first multifunctional monomer comprising vinyl groupshaving general structure (V):

wherein M, Y, Z, R₁, and R₂ are as defined above in connection withStructure (V);

with a second multifunctional monomer comprising groups that arereactive with vinyl groups having general structure (XXIII):R₃—(XH)_(2+YY)   Structure (XXIII)

wherein X, R₃, and YY are as defined above in connection with Structure(XXIII);

to yield a cross-linked polymer having general structure (I):

wherein M, X, R₁, R₂, R₃, Y, Z, and YY are as defined above inconnection with Structures (I), (V), and (XXIII).

In one embodiment, the present invention is directed to a method offorming a high refractive index material comprising a polymer having ahigh degree of cross-linking and comprising polarizable elements, whichcomprises reacting the first multifunctional monomer comprising vinylgroups having general structure (VIa):

wherein M and R₁ are as defined above in connection with Structure (V);

with a second multifunctional monomer comprising groups that arereactive with vinyl groups having general structure (XXIV):HX—R₃—XH   Structure (XXIV)

wherein X and, R₃ are as defined above in connection with Structure(XXIII); to yield the cross-linked inorganic/organic hybrid polymerhaving general structure (IIa):

wherein M, X, R₁, and R₃ are as defined above in connection withStructures (I), (V), and (XXIII).

In one embodiment, the present invention is directed to a method offorming a high refractive index material comprising a polymer having ahigh degree of cross-linking and comprising polarizable elements, whichcomprises reacting the first multifunctional monomer comprising vinylgroups having general structure (VIb):

wherein M and R₁ are as defined above in connection with Structure (V);

with a second multifunctional monomer comprising groups that arereactive with vinyl groups having general structure (XXIV):HX—R₃—XH   Structure (XXIV)

wherein X and, R₃ are as defined above in connection with Structure(XXIII);

to yield the cross-linked inorganic/organic hybrid polymer havinggeneral structure (IIIa):

wherein M, X, R₁, and R₃ are as defined above in connection withStructures (I), (V), and (XXIII).

In a preferred embodiment, the first multifunctional monomer ofstructure (VII) is reacted with the second multifunctional monomercomprising two vinyl-reactive groups reactive of structure (XXIV)according to reaction (A) below, which yields a highly cross-linkedpolymer having general structure (XXV) as shown:

wherein M, X, and R₃ are as defined in Structures (V) and (XXIV).

In one preferred embodiment, tetravinylsilane is reacted withethane-1,2-dithiol to form the highly crosslinked polymer as shown inreaction (B):

In a preferred embodiment, the first multifunctional monomer ofstructure (XV) is reacted with the second multifunctional monomercomprising two vinyl-reactive groups reactive of structure (XXIV)according to reaction (C) below, which yields a highly cross-linkedpolymer having general structure (XXVI) as shown:

wherein M, X, and R₃ are as defined in Structures (V) and (XXIV).

In a preferred embodiment, the first multifunctional monomer ofstructure (VIII) is reacted with the second multifunctional monomercomprising two vinyl-reactive groups reactive of structure (XXIV)according to reaction (D) below, which yields a highly cross-linkedpolymer having general structure (XXVII) as shown:

wherein M, X, and R₃ are as defined in Structures (V) and (XXIV).

In a preferred embodiment, the first multifunctional monomer ofstructure (XVII) is reacted with the second multifunctional monomercomprising two vinyl-reactive groups reactive of structure (XXIV)according to reaction (E) below, which yields a highly cross-linkedpolymer having general structure (XXXVIII) as shown:

wherein M, X, and R₃ are as defined in Structures (V) and (XXIV).

In one preferred embodiment,1,3,5-Triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione is reacted withbenzene-1,3-dithiol to form the highly crosslinked polymer havingstructure (IVq) as shown in reaction (F):

Other preferred reactants and polymers of the present invention areshown in the below examples.

The reaction mixture may be prepared by combining the firstmultifunctional monomer comprising alkenyl groups with the secondmultifunctional monomer comprising moieties that are reactive withalkenyl groups. In general, solvent is not necessary since the secondmonomer is generally a liquid at room temperature. In some embodiments,the relative concentrations of the first and second monomers are suchthat the functional groups are present in substantially equal molaramounts. For example, a reaction mixture comprising a firstmultifunctional monomer comprising four vinyl groups and a secondmultifunctional monomer comprising two functional groups that react withvinyl preferably contains a molar ratio of the second multifunctionalmonomer to the first multifunctional monomer of approximately 2:1, sothat the molar ratio of the functional groups are stoichiometricallybalanced. In general, an excess of the second multifunctional monomer isacceptable to ensure complete reaction of the vinyl groups. Non-reactedalkenyl groups are generally undesirable since such alkenyl groups maycause the cross-linked polymer to yellow over time.

In some embodiments, the reaction forms a prepolymer gel by contactingthe reactants at room temperature. In some embodiments, the gel is curedby transferring the gel to a mold of desired dimension and then cured inan oven between about 120° C. and about 200° C. for a durationsufficient to achieve the desired cure, typically over several hours,such as at least 10 hours, at least 15 hours, or even at least 20 hours.In general, the cure temperature affects the hardness of the finalmaterial, with cures at 120° C. resulting in a softer material and curesbetween about 150° C. and about 200° C. resulting in a harder material.The curing temperature may depend upon the materials themselves, as somematerial may discolor at higher cure temperatures. In some embodiments,the thermal processing alone is sufficient.

In some embodiments, the polymerization and cross-linking reaction maybe catalyzed by heat, radiation, or a combination of the two.Cross-linking occurs either through a photochemical process utilizing UVradiation and further curing to complete the process is often performedthermally. In some embodiments, the preparation is carried out in twosteps to achieve maximum cross-linking. In the two-stepphotochemical/heating process, the first reaction is photochemical. Thereaction mixture is thoroughly degassed to remove oxygen and placed in aseal quartz container. The reaction mixture may then be irradiatedbroadband (unfiltered) with a 250 Watt high pressure mercury arc lampfor a period of approximately 1 hour per 5 grams of solution. Theirradiation duration typically varies proportionally with the amount ofmaterials present. This results in a partially cross-linked pre-polymergel. In this state, the polymer chains have reached such a length thatthe material is viscous, but pourable. In some embodiments, the gel iscured by transferring the gel to a mold of desired dimension and thencured in an oven between about 120° C. and about 200° C. for a durationsufficient to achieve the desired cure, typically many hours, such as atleast 10 hours, at least 15 hours, or even at least 20 hours. Ingeneral, the cure temperature affects the hardness of the finalmaterial, with cures at 120° C. resulting in a softer material and curesbetween about 150° C. and about 200° C. resulting in a harder material.The curing temperature may depend upon the materials themselves, as somematerial may discolor at higher cure temperatures.

In general, at least about 70% of the functional groups, i.e., alkenylgroups and —XH moieties in the reaction mixture have reacted in theresultant highly cross-linked polymer, preferably at least 80% of thefunctional groups have reacted, and even more preferably at least 90% ofthe functional groups have reacted.

Since the polymers of the present invention are highly cross-linked, thepolymers of the present invention form a three-dimensional bulkmaterial. In view thereof, the average molecular weight of the polymeris very difficult or may even be impossible to determine Based oncurrent understandings, it is thought that average molecular weightstend to be very high, such as at least 20,000 g/mol, at least 50,000g/mol, at least 100,000 g/mol, at least 1,000,000 g/mol, or even atleast 10,000,000 g/mol.

Preferably, the high refractive index polymers produced by the processof the present invention contain hydrocarbon and second row or greatermain group elements, such as Si, Ge, or Sn. These second row or greatermain group elements have high polarizabilities, which yield highrefractive index. In preferred embodiments, the polymer of the presentinvention lacks electronegative atoms such as N and O, which are oftenfound in polymethracrylates, polycarbonates and polythiourethanes, andwhich tend to yield lower refractive index materials. In someembodiments, the materials are highly cross-linked which will yield veryhard, fracture, and scratch resistant materials. The polymers of thepresent invention also can be fabricated without optical chromophoresthat give rise to absorption in the visible region of the spectrum, suchthat the materials are therefore transparent.

Having described the invention in detail, it will be apparent thatmodifications and variations are possible without departing from thescope of the invention defined in the appended claims.

EXAMPLES

The following non-limiting examples are provided to further illustratethe present invention.

Fabrication of polymers according to the present invention was carriedout by combining various vinyl monomers (such as tetravinylsilane,1,3,5-Triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, tetra-allylsilane,and tetra-allylgermane) and thiol monomers (such as ethane-1,2-dithiol,pentane-1,5-dithiol and benzene-1,3-dithiol). The experimental detailsfor each combination and physical properties of the resulting polymershave been described in the following examples:

Example 1. Preparation of a High Refractive Index Polymer

Fabrication of a polymer according to the present invention was carriedout by reacting tetravinylsilane and ethane-1,2-dithiol according to thefollowing reaction sequence:

The reaction mixture was prepared by combining ethane-1,2-dithiol andtetravinylsilane in a molar ratio of 2 moles ethane-1,2-dithiol:1 moletetravinylsilane. To prepare the reaction mixture, ethane-1,2-dithiol(2.8 grams) was homogeneously mixed with of tetravinylsilane (2.0375 g)in a quartz container. The reaction mixture was thoroughly degassed bypassing nitrogen gas, bubble by bubble, through the reaction mixture forabout 10 minutes to remove oxygen. The quartz container was then sealed.

The reaction mixture (4.8375 g) was then subjected to photochemicalcuring by irradiating it with a 250 Watt high pressure mercury-xenon arclamp for one hour. Irradiation resulted in a partially cross-linkedpre-polymer gel. The gel was transferred to a mold of desired dimensionand then cured in an oven at 120° C. for a period of 24 hours.

The resulting cross-linked polymer was transparent, colorless, and hard.Measurement of the optical and selected physical properties of thepolymer prepared by thiol-ene coupling ethane-1,2-dithiol andtetravinylsilane is given in Table 1.

TABLE 1 Physical Properties of the Polymer Measurement Value SpecificGravity 1.19 g/cc Microhardness 2.91 Refractive Index 1.65 Abbe (vd) 38

The refractive index is in the upper range of values attained by organicpolymers, and the Abbe number is relatively low for high refractiveindex materials.

Example 2. Preparation of a High Refractive Index Polymer

Fabrication of a polymer according to the present invention was carriedout by reacting tetravinylsilane and ethane-1,2-dithiol according to thefollowing reaction sequence:

The reaction mixture was prepared by combining ethane-1,2-dithiol andtetravinylsilane in a molar ratio of 2 moles ethane-1,2-dithiol:1 moleof tetravinylsilane. To prepare the reaction mixture, ethane-1,2-dithiol(1.12 g) was homogeneously mixed with of tetravinylsilane (0.815 g) in aquartz container. The reaction mixture was thoroughly degassed bypassing nitrogen gas, bubble by bubble, through the reaction mixture forabout 10 minutes to remove oxygen and placed in a sealed glass and orTeflon container.

The reaction mixture (1.935 g) was then allowed to gel at roomtemperature which resulted in a partially cross-linked pre-polymer gelin about two days. The gel was then aged at room temperature for aboutthree days and finally cured in an oven at 120° C. for a period of 24hours.

The resulting cross-linked polymer was transparent, colorless, and hard.Measurement of the optical and selected physical properties of thepolymer prepared by thiol-ene coupling ethane-1,2-dithiol andtetravinylsilane is given in Table 2.

TABLE 2 Physical Properties of the Polymer Measurement Value SpecificGravity 1.19 g/cc Microhardness 2.91 Refractive Index 1.655 Abbe (vd) 38

Example 3. Preparation of a High Refractive Index Polymer

Fabrication of a polymer according to the present invention was carriedout by reacting tetravinylsilane and pentane-1,5-dithiol according tothe following reaction sequence:

The reaction mixture was prepared by combining pentane-1,5-dithiol andtetravinylsilane in a molar ratio of 2 moles pentane-1,5-dithiol:1 moletetravinylsilane. To prepare the reaction mixture, pentane-1,5-dithiol(1.625 grams) was homogeneously mixed with of tetravinylsilane (0.815 g)in a glass and or Teflon container. The reaction mixture was thoroughlydegassed by passing nitrogen gas, bubble by bubble, through the reactionmixture for about 10 minutes to remove oxygen.

The reaction mixture (2.44 g) was then subjected to gelation at 50° C.,which resulted in a partially cross-linked pre-polymer gel in aboutthree days. The gel was then aged at 50° C. for about three days andfinally cured in an oven at 120° C. for a period of 24 hours.

The resulting cross-linked polymer was transparent and colorless.Measurement of the optical and selected physical properties of thepolymer prepared by thiol-ene coupling pentane-1,5-dithiol andtetravinylsilane is given in Table 3.

TABLE 3 Physical Properties of the Polymer Measurement Value SpecificGravity 1.163 g/cc Refractive Index 1.590 Abbe (vd) 41

Example 4. Preparation of a High Refractive Index Polymer

Fabrication of a polymer according to the present invention was carriedout by reacting tetravinylsilane and benzene-1,3-dithiol according tothe following reaction sequence:

The reaction mixture was prepared by combining benzene-1,3-dithiol andtetravinylsilane in a molar ratio of 2 moles benzene-1,3-dithiol:1 moletetravinylsilane. To prepare the reaction mixture, benzene-1,3-dithiol(1.706 g) was homogeneously mixed with of tetravinylsilane (0.815 g) ina glass vial. The reaction mixture was thoroughly degassed by passingnitrogen gas, bubble by bubble, through the reaction mixture for about10 minutes to remove oxygen.

The reaction mixture (2.52 g) was then subjected to gelation at 50° C.which resulted in a partially cross-linked pre-polymer gel in aboutthree days. The gel was then aged at 50° C. for about three days andfinally cured in an oven at 120° C. for a period of 24 hours.

The resulting cross-linked polymer was transparent and yellow.Measurement of the optical and selected physical properties of thepolymer prepared by thiol-ene coupling benzene-1,3-dithiol andtetravinylsilane is given in Table 4.

TABLE 4 Physical Properties of the Polymer Measurement Value SpecificGravity 1.43 g/cc Refractive Index 1.687 Abbe (vd) 25.2

Example 5. Preparation of a High Refractive Index Polymer

Fabrication of a polymer according to the present invention was carriedout by reacting 1,3,5-Triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione andbenzene-1,3-dithiol according to the following reaction sequence:

The reaction mixture was prepared by combining benzene-1,3-dithiol and1,3,5-Triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione in a molar ratio of1.5 moles benzene-1,3-dithiol:1 mole1,3,5-Triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione. To prepare thereaction mixture, benzene-1,3-dithiol (1.984 g) was homogeneously mixedwith of 1,3,5-Triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione (2.318 g)in a glass vial. The reaction mixture was thoroughly degassed by passingnitrogen gas, bubble by bubble, through the reaction mixture for about10 minutes to remove oxygen.

The reaction mixture (4.3020 g) was then subjected for gelation at 50°C. which resulted in a partially cross-linked pre-polymer gel in aboutfour days. The gel was then aged at 50° C. for about three days andfinally cured in an oven at 120° C. for a period of 24 hours.

The resulting cross-linked polymer was transparent, colorless, and veryhard. Measurement of the optical and selected physical properties of thepolymer prepared by thiol-ene coupling benzene-1,3-dithiol and1,3,5-Triallyl-1,3,5-triazine-2,4,6(1H,3H,5H)-trione is given in Table5.

TABLE 5 Physical Properties of the Polymer Measurement Value SpecificGravity 1.53 g/cc Young's Modulus 706 MPa Refractive Index 1.660 Abbe(vd) 28.7

Example 6. Preparation of a High Refractive Index Polymer

Fabrication of a polymer according to the present invention was carriedout by reacting tetraallylsilane and ethane-1,2-dithiol was carried outaccording to the following reaction sequence:

The reaction mixture was prepared by combining ethane-1,2-dithiol andtetraallylsilane in a molar ratio of 2 moles ethane-1,2-dithiol mole oftetraallylsilane. To prepare the reaction mixture, ethane-1,2-dithiol(0.816 g) was homogeneously mixed with tetraallylsilane (0.834 g) in aglass vial. The reaction mixture was thoroughly degassed by passingnitrogen gas, bubble by bubble, through the reaction mixture for about10 minutes to remove oxygen and placed in a sealed glass and or Tefloncontainer.

The reaction mixture (1.65 g) was then subjected for gelation at roomtemperature which resulted in a partially cross-linked pre-polymer gelin about two days. The gel was then aged at room temperature for aboutthree days and finally cured in an oven at 120° C. for a period of 24hours.

The resulting cross-linked polymer was transparent, yellowish, and soft.Measurement of the optical and selected physical properties of thepolymer prepared by thiol-ene coupling ethane-1,2-dithiol andtetraallylsilane is given in Table 6.

TABLE 6 Physical Properties of the Polymer Measurement Value SpecificGravity 1.143 g/cc Refractive Index 1.610 Abbe (vd) 36.3

Example 7. Preparation of a High Refractive Index Polymer

Fabrication of a polymer according to the present invention was carriedout by reacting tetraallylsilane and pentane-1,5-dithiol was carried outaccording to the following reaction sequence:

The reaction mixture was prepared by combining pentane-1,5-dithiol andtetraallylsilane in a molar ratio of 2 moles pentane-1,5-dithiol mole oftetraallylsilane. To prepare the reaction mixture, pentane-1,5-dithiol(1.1831 g) was homogeneously mixed with tetraallylsilane (0.834 g) in aglass container. The reaction mixture was thoroughly degassed by passingnitrogen gas, bubble by bubble, through the reaction mixture for about10 minutes to remove oxygen and placed in a sealed glass and or Tefloncontainer.

The reaction mixture (2.017 g) was then subjected for gelation at roomtemperature which resulted in a partially cross-linked pre-polymer gelin about two days. The gel was then aged at room temperature for aboutthree days and finally cured in an oven at 120° C. for a period of 24hours.

The resulting cross-linked polymer was transparent and soft. Measurementof the optical and selected physical properties of the polymer preparedby thiol-ene coupling pentane-1,5-dithiol and tetraallylsilane is givenin Table 7.

TABLE 7 Physical Properties of the Polymer Measurement Value SpecificGravity 1.323 g/cc Refractive Index 1.570 Abbe (vd) 41.5

Example 8. Preparation of a High Refractive Index Polymer

Fabrication of a polymer according to the present invention was carriedout by reacting tetraallylsilane and 1 benzene-1,3-dithiol was carriedout according to the following reaction sequence:

The reaction mixture was prepared by combining benzene-1,3-dithiol andtetraallylsilane in a molar ratio of 2 moles pentanedithiol:1 mole oftetraallylsilane. To prepare the reaction mixture, benzene-1,3-dithiol(1.236 g) was homogeneously mixed with tetraallylsilane (0.834 g) in aglass container. The reaction mixture was thoroughly degassed by passingnitrogen gas, bubble by bubble, through the reaction mixture for about10 minutes to remove oxygen and placed in a sealed glass and or Tefloncontainer.

The reaction mixture (2.07 g) was then subjected to gelation at roomtemperature which resulted in a partially cross-linked pre-polymer gelin about two days. The gel was then aged at room temperature for aboutthree days and finally cured in an oven at 120° C. for a period of 24hours.

The resulting polymer was poorly crosslinked and did not lead toformation of three dimensional bulk material.

Example 9. Preparation of a High Refractive Index Polymer

Fabrication of polymer according to the present invention was carriedout by reacting tetraallylgermane and ethane-1,2-dithiol was carried outaccording to the following reaction sequence:

The reaction mixture was prepared by combining ethane-1,2-dithiol andtetraallylgermane in a molar ratio of 2 moles ethane-1,2-dithiol:1 moleof tetraallylgermane. To prepare the reaction mixture,ethane-1,2-dithiol (0.810 g) was homogeneously mixed withtetraallylgermane (1.015 g) in a glass container. The reaction mixturewas thoroughly degassed by passing nitrogen gas, bubble by bubble,through the reaction mixture for about 10 minutes to remove oxygen andplaced in a sealed glass and or Teflon container.

The reaction mixture (1.825 g) was then subjected for gelation at roomtemperature which resulted in a partially cross-linked pre-polymer gelin about two days. The gel was then aged at room temperature for aboutthree days and finally cured in an oven at 120° C. for a period of 24hours.

The resulting cross-linked polymer was transparent, yellowish, and hard.Measurement of the optical and selected physical properties of thepolymer prepared by thiol-ene coupling ethane-1,2-dithiol andtetraallylgermane is given in Table 8.

TABLE 8 Physical Properties of the Polymer Measurement Value SpecificGravity 1.192 g/cc Refractive Index 1.62 Abbe (vd) 39.9

Example 10. Preparation of a High Refractive Index Polymer

Fabrication of polymer according to the present invention was carriedout by reacting tetraallylgermane and pentane-1,5-dithiol was carriedout according to the following reaction sequence:

The reaction mixture was prepared by combining pentane-1,5-dithiol andtetraallylgermane in a molar ratio of 2 moles pentane-1,5-dithiol:1 moleof tetraallylgermane. To prepare the reaction mixture,pentane-1,5-dithiol (1.168 g) was homogeneously mixed withtetraallylgermane (1.015 g) in a glass container. The reaction mixturewas thoroughly degassed by passing nitrogen gas, bubble by bubble,through the reaction mixture for about 10 minutes to remove oxygen andplaced in a sealed glass and or Teflon container.

The reaction mixture (2.183 g) was then subjected for gelation at roomtemperature which resulted in a partially cross-linked pre-polymer gelin about two days. The gel was then aged at room temperature for aboutthree days and finally cured in an oven at 120° C. for a period of 24hours.

The resulting cross-linked polymer was transparent and soft. Measurementof the optical and selected physical properties of the polymer preparedby thiol-ene coupling pentane-1,5-dithiol and tetraallylgermane is givenin Table 9.

TABLE 9 Physical Properties of the Polymer Measurement Value SpecificGravity 1.225 g/cc Refractive Index 1.59 Abbe (vd) 45

Example 11. Preparation of a High Refractive Index Polymer

Fabrication of polymer according to the present invention was carriedout by reacting tetraallylgermane and benzene-1,3-dithiol was carriedout according to the following reaction sequence:

The reaction mixture was prepared by combining benzene-1,3-dithiol andtetraallylgermane in a molar ratio of 2 moles benzene-1,3-dithiol:1 moletetraallylgermane. To prepare the reaction mixture, benzene-1,3-dithiol(1.223 g) was homogeneously mixed with of tetraallylgermane (1.015 g) ina glass vial. The reaction mixture was thoroughly degassed by passingnitrogen gas, bubble by bubble, through the reaction mixture for about10 minutes to remove oxygen.

The reaction mixture (2.238 g) was then subjected for gelation at roomtemperature which resulted in a partially cross-linked pre-polymer gelin about three days. The gel was then aged at room temperature foranother three days and finally cured in an oven at 120° C. for a periodof 24 hours.

The resulting cross-linked polymer was transparent and hard. Measurementof the optical and selected physical properties of the polymer preparedby thiol-ene coupling benzene-1,3-dithiol and tetraallylgermane is givenin Table 10.

TABLE 10 Physical Properties of the Polymer Measurement Value SpecificGravity 1.216 g/cc Refractive Index 1.69 Abbe (vd) 24.3

Example 12. Fabrication of Polymer/Nanoparticle Composites

Materials

Monomers viz. 1,2-ethanedithiol, 1,5-pentanedithiol, 1,3-benzenedithiol,1,3,5-Triallyl-1,3,5-triazine-2,4,6-trione, acrylic acid were purchasedfrom Sigma-Aldrich and were used as received. Tetravinylsilane and1,3,5,7-tetravinyl-1,3,5,6,7-tetramethylcyclotetrasiloxane were orderedfrom Gelest and were used without further purification. The nanopowdersof TiO₂ and ZrO₂ were purchased from US Research Nanomaterials, Inc.

The Fabrication of Polymer Composites Involved Two Major Steps:

Surface Modification of TiO₂/ZrO₂ Nanoparticles by Acrylic Acid

In order for nanoparticles to take part in polymerization process andthus get chemically bonded with the host polymer matrix, the surface ofthese nanoparticles was modified with acrylic acid. The purpose ofsurface modification was to replace a partial amount of surface hydroxylgroups on the nanoparticles by vinyl groups in the acrylic acid. Thereaction was carried out by dispersing 1 g of nanoparticles in anaqueous solution of acrylic acid (1.6 g of acrylic acid in 200 ml ofwater) and gradually replacing water with methanol in a rotaryevaporator. The chemical reaction of acrylic acid on the surface ofthese particles takes place according to FIG. 1.

In-Situ Incorporation of TiO₂/ZrO₂ Nanoparticles

The surface modified nanopowders were ground using mortar and pestlebefore use to breakdown the agglomerates into smaller particles. Thevarious steps involved in the fabrication of polymer-nanoparticlecomposites are depicted in FIG. 2.

In order to separate out the heavier particles and to obtain stableparticle dispersion, the nanoparticles were added in excess (0.2 wt %)to the mixture of thiol-ene monomers prepared under stoichiometricconditions (the number of vinyl groups equal thiols). The resultingreaction mixture was turbid as it had bigger particles (>30 nm) toscatter the light. The desired optical transmission was accomplished bycentrifuging (3-5 min at 1000 rpm) the reaction mixture until it becomestransparent (>90%). At this point, the top transparent portion of themonomer mixture, containing extremely small size nanoparticles (<10 nm),was transferred to the desired container and was allowed to polymerizeat room temperature. Final curing of these pre-polymer gels at 120° C.in a furnace yielded highly transparent and rigid polymer composites.

Table 11 summarizes optical, mechanical and thermal properties ofvarious polymer composites obtained by incorporation of TiO₂ and ZrO₂nanoparticles.

TABLE 11 Refractive Storage Modulus Tg (° C.) Polymer Composite Index(MPa) [DMA] TVG-BDTH-TiO₂ 1.730 (1.692) 25 (627) * * * (56) TVG-BDTH-ZrO₂ 1.725 (1.692) 600 (627)  45 (56) TTT-BDTH-TiO₂ 1.667(1.660) 8000 (551)  71 (66) TTT-BDTH-ZrO₂ * * * * * * * * *TVS-BDTH-TiO₂ 1.720 (1.687) 1550 (668)  52.54 (69)   TVS-BDTH-ZrO₂ 1.716(1.687) 4400 (668)  42 (69) TVS-EDTH-TiO₂ 1.669 (1.656) 50 (108) 40 (42)TVS-EDTH-ZrO₂ 1.668 (1.656) 20 (108) 30 (42) TeSO-BDTH-TiO₂ 1.667(1.660) 16 (520) 25 (38) TeSO-BDTH-ZrO₂ * * * * * * * * *

Although the titanium oxide and zirconium oxide nanoparticles used inthe examples described above were derivatized with acrylic acid, itshould be understood that derivatization can be conducted by reactionwith any monomer that comprises both a vinyl group and a functionalgroup that is reactive with hydroxyl ions or oxide moieties of thenanoparticle substrate. Also, the nanoparticle may consist of orcomprise metal oxides other than titania or zirconia. Other nanoparticlematerials may include oxides of hafnium, niobium, molybdenum, tantalum,tungsten, tellurium, and in fact essentially any transition metal. Toprepared the composite that comprise a thiol-ene polymer matrix andnanoparticles dispersed within the matrix, a charge mixture is formedcomprising a first multifunctional monomer comprising vinyl groups, asecond multifunctional polymer comprising thiol moieties, andnanoparticles dispersed in the monomer phase. Optionally, the mixture iscentrifuged to substantially remove relatively larger particles from thedispersion. For example, it may be desirable to substantially removeparticles having size of more than 100 nm, or more than 50 nm, or morethan 30 nm.

The first multifunctional monomer is reacted with the secondmultifunctional monomer in the monomer/nanoparticle dispersion to form apolymer matrix within which the nanoparticles are dispersed. Preferablythe metal oxide is covalently bonded to the matrix polymer, e.g., byreaction of metal oxides or metal hydroxide at the particle surface, ormore preferably by reaction of a ligand comprising a vinyl group withwhich the nanoparticle is derivatized, with functional groups of thefirst multifunctional monomer, functional groups of the secondmultifunctional monomer, or functional groups of a polymer produced byreaction of the first monomer and the second monomer. To form thematrix, any of the dithiol monomers described above can be reacted witha multifunctional monomer that preferably comprises a silane, germane,or organotin compound having 2 to 4 ethylenically unsaturated ligandssuch as, e.g., vinyl or allyl (vinylmethyl). (Meth)acrylic ligands orother ligand structure which comprises a vinyl group are reactive with,and react with, the dithiol monomer, polythiol monomer, or correspondingmonomer comprising phosphinyl, selenol, or arsininyl groups. A vinylligand on the nanoparticle may also react with a vinyl group of anothermultifunctional monomer that has a plurality of vinyl groups, althoughthat reaction is not favored in the absence of a free radical catalyst.

The reaction proceeds by formation of a prepolymer gel, and curing ofthe prepolymer gel to form the composite product. Formation of theprepolymer gel is self-initiated in that it proceeds in the absence ofany initiating additive, i.e., the charge mixture and the reactingmixture do not contain any photoinitiator, free radical catalyst orinitiating additive. Self-initiated polymerization, as that term is usedhere, does not exclude exposing the polymerizing mixture to heat orlight, including ultraviolet light, but it does exclude the use of aphotoinitiator or other similar additive. Curing is typically effectedby heating the mixture comprising the prepolymer gel. Preferably,photoinitiators and free radical catalysts are excluded from the curingstage as well.

Fabrication of Polymer/Oxo-Zirconium Cluster Composites Example 13

Oxozirconium methacrylate clusters type A: Zr₆(O—H)₄O₄(Methacrylate)₁₂and type B: Zr₄O₂(Methacrylate)₁₂ were obtained by reaction of Zr(OnPr)₄with an excess of methacrylic acid. In a typical example, 3.1 mmol ofZr(OnPr)₄ was reacted with 11.8 mmol of methacrylic acid under Aratmosphere free from moisture. Type A crystals precipitated out in aboutfive of days and were transferred in a separate vial. In an anotherexample, 3.1 mmol of Zr(OnPr)₄ was reacted with 48 momol of methacrylicacid under Ar atmosphere to yield type B crystals which wereprecipitated out in couple of days.

Example 14

In addition to the type A and type B crystals, two more types ofoxozirconium crystals (type C: Zr₆(O—H)₄O₄(acrylate)₁₂ and type D:Zr₄O₂(acrylate)₁₂) were synthesized by reacting Zr(OnPr)₄ with excessacrylic acid under Ar atmosphere. The molar ratios of Zr(OnPr)₄ toacrylic acid were the same as given in Example 13.

Example 15

The crystals were washed with excess non-polar solvent such as hexane toremove any unreacted Zr(OnPr)₄. The polymer composites were fabricatedby dissolving 1 wt % of type A, type B, type C and type D crystals inthiol-ene monomer mixture obtained by combining tetravinylsilane andbenzenedithiol in a stoichiometric molar ratio (i.e. 1:2). The monomermixtures were then allowed to form pre-polymer gels and were finallycured in an oven at 120° C. to yield rigid polymer composites. Therefractive indices of these polymer composites were 1.720, 1.715, 1.716and 1.714 for type A, type B, type C and type D, respectively.

Preparation of a transparent polymeric material from a firstmultifunctional monomer, a dithiol (or polythiol, or correspondingmonomers comprising phosphinyl, selenol or arsinyl groups, and amolecular metal oxide cluster is particularly advantageous because themolecular metal oxide cluster is soluble in a mixture comprising theother monomers, and can be uniformly distributed throughout the chargemixture without risk of sedimentation, and enables the preparation ofsingle phase hard, transparent optical material.

In preparing a polymer composition or polymer matrix incorporating amolecular metal oxide cluster, n moles of a first multifunctionalmonomer having a plurality of, e.g., 2 to 4 vinyl groups is reacted withm moles of the molecular metal oxide cluster, and a dithiol, otherpolythiol, or other corresponding monomer comprising phosphinyl, selenolor arsinyl groups, in a proportion sufficient to react with the vinylgroups of the first multifunctional monomer and the molecular metaloxide cluster. For example, a bulk copolymer capable of use as ahomogeneous, single phase optical material or as a matrix fornanoparticulates of a composite material can be prepared by thereaction:nSi(CH═CH₂)₄ +mZr₆(OH)₄O₄(O₂CH═CH₂)₁₂+(2n+6m)HSCH₂CH₂SH→

The first multifunctional monomer, in this case Si(CH═CH₂)₄, ispreferably in substantial excess over the molecular metal oxide cluster,i.e., n>>m. For example n may have a value between 10 m and 1000 m, morepreferably between about 50 m and about 200 m. In terms of equivalents,these ratios are typically lower because of the high number of vinylgroups in the molecular metal oxide cluster. In the equation above, amolar m/n ratio of 10 reduces to an equivalents ratio of 3.3, a molarratio of 50 reduces to a equivalents ratio of 17 a molar ratio of 200reduces to an equivalents ratio of 67, and a molar ratio of 1000 reducesto an equivalents ratio of 333.

Exemplary metal oxide clusters that may participate in a polymerizationreaction with a first multifunctional monomer having a plurality ofvinyl groups, and a dithiol, polythiol, poly(phosphonyl), poly(selenol),or poly(arsinyl) monomer, include Zr₆(OH)₄O₄(O₂CH—CH₂)₁₂,Zr₄O₂(O₂CH—CH₂)₁₂: Zr₆(OH)₄O₄(O₂C(CH3)=CH₂)₁₂ and Zr₄O₂(O₂C(CH₃)═CH₂)₁₂.Comparable molecular metal oxide clusters can be based on oxides ofother transition metals such as Ti, Hf, Ni, W, Mo, Te and Ta.Compositions of such structures may be identical to the Zr oxidestructures with adjustments in the number of (meth)acrylic ligands thatmay result from differences in the oxidation state of the transitionmetal.

Where a Zr oxide cluster is reacted with m-dimercaptobenzene and a firstmultifunctional monomer such as an “M” moiety ligands that comprise 2, 3or 4 vinyl groups, e.g., a dimethyl divinyl silane or dimethyl divinylgermane, polymer product includes repeating units having the structure

where M is sulfur, silicon, tin, or an organic moiety. If the firstmultifunctional compound is a trivinyl alkyl or tetravinyl silane orgermane, the polymeric structure that includes derivatized metal oxidewill proliferate via a more complex network formed by cross-linking atthe unsaturated substituents on “M”. Comparable structures can beprepared from molecular clusters of other metal oxides such as oxides ofTi, Hf, Nb, Mo, W, Te, Ta, or other transition metals.

Polymerization of a first multifunctional compound, a dithiol,pollythiol or corresponding monomer comprising phosphinyl, selenol orarsinyl groups, and a molecular metal oxide cluster forms a transparentmaterial that has a high degree of clarity and hardness, and a highrefractive index. Such material can be used as a matrix fornanoparticulate metal oxides, including metal oxides that have beenderivatized with ligands that include vinyl groups that can react withthe thiol, vinyl groups of the first monofunctional polymer or vinylgroups of the molecular metal oxide. Alternatively, the firstmultifunctional monomer, dithiol or polythiol, and molecular metal oxidemay be polymerized from a charge mixture that is substantially orentirely free of particulates to yield a product that consists of asingle phase homogeneous structure, not a matrix comprising dispersedparticles of any nature. This polymerization product is highlytransparent, has a high index of refraction, exhibits high hardness, hasa high Abbe number, and is therefore useful for various opticalapplications. For example, lenses constituted of such material have highAbbe numbers, e.g., at least 38, are wear-resistant, and are highlyuseful in transforming and focusing light waves. Prisms of such materialare highly effective for separating light of different wave lengths.

In view of the above, it will be seen that the several objects of theinvention are achieved and other advantageous results attained. Asvarious changes could be made in the above compositions and processeswithout departing from the scope of the invention, it is intended thatall matter contained in the above description and shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense. When introducing elements of the present invention orthe preferred embodiments(s) thereof, the articles “a”, “an”, “the” and“said” are intended to mean that there are one or more of the elements.The terms “comprising”, “including” and “having” are intended to beinclusive and mean that there may be additional elements other than thelisted elements.

The invention claimed is:
 1. A bulk polymer composite comprising athiolene polymer matrix and metal oxide nanoparticles dispersed withinsaid matrix, said nanoparticles being bonded to polymer moleculescontained in the matrix; wherein said polymer comprises repeat unitsderived from a first multifunctional monomer comprising a plurality ofvinyl groups, a polythiol, and a molecular metal oxide cluster, and saidrepeat units correspond to the structure

where M is sulfur, silicon, tin, or an organic moiety; and where n isthe number of repeat units.
 2. The bulk polymer composite as set forthin claim 1 wherein the nanoparticles are ≦00 nm in size as incorporatedinto a monomer formulation from which the polymer is prepared.
 3. Thebulk polymer composite as set forth in claim 1 wherein the value of n isbetween 10 and
 1000. 4. The bulk polymer composite as set forth in claim1 wherein the value of n is between 50 and
 200. 5. The bulk polymercomposite as set forth in claim 1 wherein M is the sulfur.
 6. The bulkpolymer composite as set forth in claim 1 wherein M is the silicon. 7.The bulk polymer composite as set forth in claim 1 wherein M is the tin.8. The bulk polymer composite as set forth in claim 1 wherein M is theorganic moiety.
 9. The bulk polymer composite as set forth in claim 1wherein the composite is incorporated into a corrective lens.
 10. Thebulk polymer composite as set forth in claim 1 wherein the composite hasa refractive index of at least 1.65.
 11. The bulk polymer composite asset forth in claim 1 wherein the composite has a refractive index of atleast 1.65 and an Abbe number of at least 38.